This paper describes a fiber optic local area network which has been designed for use as an Ethernet and is currently operating at the Xerox Palo Alto Research Center. The fiber optic network, named Fibernet II, is an active-star configured network which is plug compatible with Ethernet at the transceiver cable interface. Collision detection is performed in the active star and collision presence is transmitted to the Fibernet transceivers. The performance and capabilities of Fibernet II are presented along with the motivation for the particular fiber optic implementation that was realized.

This paper applies the Gram-Charlier series method to the caculation of error probabilties in digital optical receivers. This method allows the calculation of "exact" error probabilities including the effects of avalanche noise, thermal noise, and arbitrary posidetection processing filter. The predictions of this method are compared with those of a simple Gaussian approximation and with the Chernoff bounds. Finally, the effects of modal noise are included in the theory, and some specific cases are explored numerically.

Local computer networks which communicate over copper conductors have been developed both to promote resource sharing and provide increased performance. Such networks typically operate at bandwidth-length (Bw \circ L) products up to a fewMHz \circ km. In this paper we consider the use of fiber optics in such networks, and give a status report on a star-configured fiber optic network experiment called Fibernet which operates at aBw \circ Lproduct of\sim 100 MHz\circ kmat a data rate of 150 Mbits/s and which in its final phases will connect up to 19 stations. We compare the merits and problems of linear, ring and several star configurations, and of active versus passive networks. The packet communication protocol is discussed and network efficiency is calculated as a function of the packet length, channel capacity and network propagation time. We describe the system performance of the present Fibernet experiment, which uses a 19-port transmissive star coupler, GaAIAs injection lasers and avalanche photodiodes, and incorporates bi-phase data encoding. Power distribution inhomogeneities, observed in the output of the transmissive star coupler's mixer rod, are explained geometric-optically.